Treatment of wool and other animal fibers



Patented Aug. 22, 3950' TREATMENT OF WOOL AND OTHER ANIMAL FIBERSLeendert Maaskant, Arnhem, Netherlands, as-

signor to American 'Enka Corporation, Enka, N. 0., a corporation ofDelaware No Drawing.

Application Februa y 18, 1948, Se-

rial No. 9,333. In the Netherlands June 28,

11 Claims.

The present invention relates to the treatment of animal fibers andproducts formed therefrom. More particularly, the invention is directedto a method of improving the physical and chemical properties of wooland other animal fibers, yarns, fabrics, knitted materials andfinishedarticles.

One of the most important of these materials is wool because of itswarmth-insulating property its comfort of wearing and the ease withwhich it can be spun into fibers and fulled dur-- ing processing forcertain purposes. Wool also has an appreciable resistance to acids whichrenders it suitable for certain types of clothing used in places whereprotection against acid is necessary. This acid-resisting property ofwool renders it suitable for filter cloth and filter bags for thefiltration of acid solutions, although its durability in this respect islimited and the treatment comprehended by the present invention makes itpossible to use wool more intensively for certain purposes.

On the other hand, the strength properties and some chemical propertiesof wool are not so favorable. One of the most important failings of woolis its sensitiveness to alkalies so that the utmost caution must beexercised to prevent it from coming into contact therewith. Even in anormal washing operation using a weakly alkaline soap solution atmoderate temperature, this disadvantage is noticeable, and a boilingoperation with dilute soap or soda solutions is entirely impracticable.In general, wool and other animal fibers are also sensitive to bleachingwherein it or they are not sufficiently resistant to chlorine treatment(hypochlorite). Another disagreeable property of wool is that it issubject to destructure which is peculiar to wool and which cannot besaid of artificial textile products such as viscose rayon, casein ornylon threads which are spun from a homogeneous viscous solution.

In my co-pending application Serial No. 760,- 936, filed July 14, 1947,there is disclosed and claimed a process and product involving theaftertreatment of synthetic protein products such as casein withprecondensation products of an aldehyde and resorcinol or a substitutedresorcinal. However, it could not'be determined that such treatmentwould be applicable to animal fibers such as wool, because wool ischaracterized by a special fibrous keratin structure which is based on atridimensional network of --S-S- bridges (sulphur bridges) whereascasein may be considered a phosphor proteid of the globulin type,wherein there exists no real fiber structure.

Therefore, the dissolving properties of the two proteid substancesdifier in principle, in that, whereas wool is hydrolyzable under certaincircumstances, particularly with alkalies, it is not normally easilysoluble. On the other hand casein dissolves in a dilute ammoniasolution. However, the behaviour of a technical thoroughly hardenedcommercial casein is again quite different. Wool, for example,hydrolyzes completely under proper conditions and may be dissolved whenit is treated for one houiwith a 4% caustic soda solution at 50 C. Undersimilar conditions, the normal commercial casein thread dissolves onlyto a very limited extent, i. e., often less than 1%.

Various attempts have been made to improve the properties of wool andother animal fibers or hair by a suitable aftertreatment. When certainprecautions are observed, it was determined that the creasing andwater-absorbing power could be decreased by a treatment withprecondensation products from phenol or urea and formaldehyde or theircomponents, followed by a hardening on the fiber. It was determined,however, that local deposits of the resin were often formed on thesurface of the fiber which resulted in their sticking together. Whenthis occurred, it gave rise to a decrease in resistance to abrasion andto creasing, and in addition the softness of the fiber decreased. Thetreatment with these precondensation products only improved the chemicalproperties of the wool to a very small extent. Theurea-formaldehyde-condensation-products which were deposited on thewool, or were condensed on it, were not resistant to acids or even toboiling water, but due to hydrolysis were dissolved.

Neither the treatment with urea-formaldehyde-condensation-products norwith phenolformaldehyde condensation products protects wool and otheranimal fibers sufficiently against alkalies. The experiments showed thatthe low degree of protection afforded by these substances was due to thefact that the condensation products only enveloped the fiber and actedmuch the same as an armor or film-like coat. It is also possible thatthese condensation products penetrate under the scales of the wool andinto the crevices, but it is believed that the wool or hair is notchanged and does not combine chemically with the condensation products.

It is therefore an object of the present invention to provide a processfor the aftertreatment of wool and other animal fibers, intermediateproducts and finished products manufactured from them, and also fleeces,whereby the chemical and physical properties of the materials aresubstantially improved.

It is a further object of this invention to treat wool fibers and thelike with precondensation products that actually react chemically withthe fiber itself so that the fiber is at least partially modifiedchemically, i. e., its sensitive or reactive groups are blocked orcombined with the precondensation products.

Another object of this invention is the production of an improved animalfiber and articles formed therefrom which has been treated with aprecondensation product of an aldehyde with resorcinol or withsubstituted resorcinols.

According to the invention an aqueous acid precondensation solution isprepared by dissolving resorcinol in an approximately 35% formaldehydesolution in a ratio of one gram-molecule of resorcinol to at least 6gram-molecules of formaldehyde. By heating this solution at about 60 C.for about one-half hour, it is brought to the proper stage ofprecondensation. The pH of this concentrated resorcinol formaldehydesolution should be adjusted to a value between 4.5

and 2.8. Next, the solution is diluted with water until theconcentration of the originally dissolved resorcinol is 0.5% to 1.0%.The pH value of this dilute solution should be adjusted to a valuebetween 45 and 5.5, at which time it is in condition for the treatmentof wool.

At room temperature or at a slightly higher temperature (40 C.) theprecondensation solution is very stable, i. e., the condensation processcontinues very slowly.

Next, the wool is treated with the precondensation solution byimmersion, preferably at an increased temperature at about 40-45 C. Itwas determined that the precondensation product was substantivelyabsorbed by the fibers. After centrifuging and drying the wool productis then heated above 100 0., preferably at about 105 C., for aboutone-half an hour, whereby the product is hardened.

It is to be noted from the above description of the preparation of theprecondensates that the precondensation solution must be acid and that alarge excess of formaldehyde must be used, and although this preparationcan be varied within wide limits, the pH value must be maintained withinthe limits given above, or otherwise the condensation reaction maycontinue to an undesired stage both in the concentrated solution andafter dilution. If the pH value of the solution lies outside of thepreferred range, this value can be corrected by the addition of weakalkalies or acids. If an acid is required, lactic acid is advisable.

It is important that these precondensates are substantively absorbed,because then dilute solutions can be employed which reduce losses, andalso the sticking together of the fibers is minimized, whereby the woolproducts treated with the precondensates have an increased pliability.In view of this substantivity and reactivity of theresorcinol-formaldehyde precondensates with respect to wool, the effectsare entirely different from those which are obtained by means of urea-,phenolor melamine precondensation products. These last three productseffect only very little improvement in the chemical property of wool.

In general, it was determined that effective results were obtained bydepositing about 5% of the precondensation product on the wool. Theabsorption is dependent on various factors such as the temperature atwhich the treatment takes place, the concentration of the solution, theliquid ratio and the time of immersion. Other things being equal, thequantity absorbed increases within certain limits with the temperatureapplied during the treatment, the concentration of the solution and theliquid ratio. Thus, in practice, the quantity to be absorbed can bepredetermined and regulated by the proper selection of workingconditions. In any case, it is advisable to use an excess of theprecondensation product.

These precondensation products can be used with beneficial results onwool fiock, immediately after washing the wool and also on yarns,fabrics, knitted materials and even on finished articles such as woolcloth out to size, filter cloth, woolen filter bags, woolen clothing,including protective clothing, woolen carpets, and also on other animalhairs such as horse hair, cow hair, hogs hair, felt from wool or hairs,and even fieeces. For convenience and brevity, these materials arereferred to hereinafter as keratinaceous animal fibers, this term beingemployed to refer to such fibers whether present in the form of fibersas such or as finished articles including such fibers.

The following examples serve to illustrate various applications of theprecondensates to wool fibers and the like and products formed therefrom.

EXAMPLE 1 500 gms. resorcinol were dissolved in 3 liters of a, 36%formaldehyde solution. This mixture was heated for 30 minutes at 60 C.(pH=3.4). After cooling, 4'] liters of water were added. The pH of thesolution was then 4.8. Thereupon 2 kilograms of freshly washed woolfibers were thoroughly rinsed, centrifuged and immersed in this 50 litersolution at room temperature. While stirring at intervals the wool wasleft in this solution for 30 minutes. It was then centrifuged, dried atC. and finally heated at C.

EXAMPLE 2 Unfinished woolen cloth was treated for A or an hour at 40 C.in a vat containing a dilute solution of the precondensation productsprepared in accordance with'Example l. The cloth was then withdrawn,hydroextracted, and dried in a drying room at 70 C. and finally hardenedfor 30 minutes at 105 C.

Examples 1 and 2 were conducted under identically the same conditionswith the exception that a substituted resorcinol was used instead ofresorcinol, namely, 1-3-dihydroxy-6-chloro-benzene was used. In thiscase the quantities were modified in accordance with the difference inmolecular weight between resorcinol and its substitution product.

3, it was determined that after the same acid treatment, the strengthhad decreased to a far lesser extent. The comparative strengths weredetermined on strips of a width of 30 mm.

EXAMPLE 3 A dilute precondensation solution was prepared fffgg im gz bydissolving 5 parts of resorcinol in 40 parts of a 36% formaldehydesolution. The solution was dry Wet dry wet adjusted to a pH of 3.4 andheated for 30 minutes at 60 0. and finally diluted with cold water. kg.km W M This precondensation solution contained 10 untreated 4.3 3.5 5.02.2 grams of resorcinol and 80 grams of forinaldetreated hyde solutionper liter calculated on the original chemicals. Finished woolenarticles, 1. e., cloth- From the above it can be Seen that the strengthing and filter bags were introduced into a rotatof the trefited fabricin both the dry and Wet ing drum, together with 2 times as much of thestate has increased greatly over that of the undilute precondensationsolution. While rotating treajted fabricthe drum slowly, the articleswere treated at 40 3 F11$r$ags g fiz fi 5 3 1 3 y w c were use or re.ion 0 o aci fi if fi flg gfgi {i s mfi g fij ggs :0 spinning baths,showed that they had about centrifuged and dried at and hardened bytwice the life of the untreated ones. Moreover, exposing them to a hotair current of 105 C. for the Woolen protectiv? clothing worn byOperaminutes. tors in rayon factorles was substantially more EXAMPLE 4durable than untreated woolen protective clothe" in worn under the sameconditions. A preconden-sation solution was prepared by 0 g dissolving 5parts of resorcinol in 40 parts of a Hzgher resistance to Qmomwtreatment 33% formaldehyde solution. The solution was (hypochlonte)djusted to a p of heated at f The treated and untreated material wassub- 30 minutes and diluted with water. This solution 30 jected t a veryintensive chlorine treatment contain d 5 em 0 f r s l and 40 grams of(bleaching operation). After this treatment formaldehyde solutlon perliter calculated on the hi was somewhat exaggerated the untreatedoriginal chemicals. A fulled felt was introduced t i l Showed a numberof large holes While to a p e f 25 s as m1 10h 0f the treated materialstill had a good appearance. pr ec9ndensatlon Solutlon- Whlle qlrculetmg35 In order to further illustrate the effects of this stirrin slowly,the felt was treated in thlsvat at intensive treatment, the strengths fstrips of 35 o. for 6 hours. The felt was then centr fug the treatedand. untreated material were measagain exposed to the impregnatingsolution for a, d are as follows; 30 minutes, centrifuged a second timeand dried in the air, and after this, completely dried at 70 I C.Finally, the felt was hardened in a hot air t l ii w l tttif current at105 C.

In the above examples, and with reference dry wet dry wet moreparticularly to Example 3, the articles were tested and found to have anumber of improved 4:, m ft m m lg. kg. kg. 0- phlg i d em allfiloperties. tA OIfIID entities;fitiii tifive fiiis t 0' ese proper ieso e proper ies 0 an uns -7 1.3 90 treated article will be given indetail below.

a.,1ncrease in the strength of the fabric Decrease m shrinkage For thepurpose of this experiment the fi i i i standmid strengths weredetermined on strips of 50 mm. as g proce ure W Ou any spam mecham' inwidth. cal treatment. Pieces of thin wool cloth were used for thisexamination.

Direction of Direction oi the warp a the weft Warp Weft dry wet dry WetV UNTREATED k #9- aai i stiilti f untreated 68.6 56-6 45-9 7- 6O5washings... treated 84.1 63-0 5 -8 8- l0 washings..;

The above shows that after treatment, the \r f g l sg gg on cloth)strengths of the strips have increased both in y the direction of thewarp and of the weft. us shrinkage 8MP b. Increased resistance to acidiltiifiifigi 13 $1.

h An untreated woolen fabric was treated with 10 was mgs 3 3 3 0 N/lsulphuric acid at 95 C. for 4 hours. A com siderable part of the keratinprotein was dis- Increase of the abrasion resistance solved while thestructure of the fabric had dis- Abrasion measurements were carried outwith appeared for the greater part. The strength of the Schopperabrasion machine. The load durthe fiber was only a small fraction ofthat before ing the measurement was 2 kg. and the number the treatment.However, when the wool maof rotations amounted to 2000. All the samplesterial had been treated as described in Example were tested under theseconditions.

The loss in thickness determined by means of the Schopper thicknesstester at the places, which had not been exposed to abrasion and whichhad been exposed to abrasion was practically equal in both cases (about2.5%). The strip strength was determined of the exposed parts in thedirection of the warp threads. The width of these strips was 2%; cm. andthe length about 4 cm. The strip strength found at the places exposed toabrasion of the untreated and treated wool material were as follows:

strip strength (average of 4 determinations) of untreated material 1.3kg. Strip strength (average of 4 determinations) of treated material 4.5kg.

These figures show, that the resistance to abrasion has increased afterthe treatment (4.5% resin on cloth).

1. Increase of the resistance to moths Experiments showed that after thetreatment the wool material was appreciably more resistant to moths.This investigation was conducted by the Vezelinstituut T. N. O. atDelft, Holland. The result of the experiment, which comprised generallythe subjection of treated and untreated woolen fabric to moths which hadbeen cultivated in the Vezelinstituut, was as follows: Both theuntreated and the treated fabrics have been attacked. There is, however,a clear difference visible in the degree of attack. The attack of thesample marked in red is less strong. If the attack of the untreatedfabric is assumed to be 100, at a visual estimation the attack of thesample marked in blue is 75 and that of the fabric marked in red 20.This is quoted from the Report of the Vezelinstituut, wherein the samplemarked in blue refers to the material treated with formaldehyde only,whereas the sample marked in red has been treated with theprecondensation products of resorcinol and formaldehyde.

Further samples were submitted to the Vezelinstituut in which theuntreated ones and the ones treated with formaldehyde were uncoloured,and the ones treated with precondensation products of resorcinol andformaldehyde were coloured. Quoting from the findings by theVezelinstituut, the Report reads as follows: Both the coloured and theuncoloured pieces of fabric had been attacked by moth-larvae. Thecoloured sample has been shorn only superficially; the uncolouredsamples have been damaged moderately, while holes are present in them."

The above experiment clearly shows that the material treated withresorcinol formaldehyde precondensation products has a better resistanceto moths.

9. Higher resistance to alkalies A treated and untreated piece of woolencloth were introduced into a N/l NaOH solution at room temperature forabout minutes. At the end of this time the percentage of dissolved woolwas determinedand it was found that of the treated material haddissolved, whereas of the untreated material had dissolved.

Referring now in general to the hardening of the precondensation on thefibers, it is to be 'pointed out that this can be effected at atemperature slightly above C. As mentioned in the examples, theoperations can be conducted successfully at C. However, it wasdetermined that it was not desirable to exceed 140 C.

during the hardening operation due to the sensitiveness of the wool tohigher temperatures. As a matter of fact, it was found that it was notnecessary to raise the temperature above C. when operating in accordancewith the present invention.

In addition to the improved properties specifically mentioned anddetermined as pointed out above, the fibers show practically no tendencyto stick together, and as a result of which the products exhibit aremarkable softness.

What is claimed is:

1. A process of improving the physical and chemical properties ofkeratinaceous animal fibers, which comprises the steps of treating thefibers with a weakly acidic solution containing precondensation productsof (a) formaldehyde and (b) a compound of the class consisting ofresorcinol and chloro-substituted resorcinols in the preparation ofwhich at least six mols of (a) per mol of (b) are employed, centrifugingthe thus treated fibers and drying the same by heating.

2. A process according to claim 1 wherein the precondensation productsare of formaldehyde and resorcinol.

3. A process according to claim 1 wherein the precondensationproductsare of formaldehyde and 1.3 dihydroxy 6. chloro-benzene.

4. In a process of improving the physical and chemical properties ofkeratinaceous animal fibers, the steps which comprise dissolving (b) acompound of the class consisting of resorcinol and chloro-substitutedresorcinols in an aqueous acid solution of (a) formaldehyde having a pHvalue between 5 and 2.8, the molecular ratio of (a) to (b) being atleast 6:1, heating the solution to a temperature of the order of 60 C.for a period of about one-half hour whereby there are formedprecondensation products, adding animal fibers to the solution andsubjecting the same to treatment therewith for about one-half hour whilemaintaining the temperature of the solution at 40-45 C., removing anddrying the fibers and hardening at a temperature above 100 C.

5. A process according to claim 4 wherein the precondensation productsare of formaldehyde and resorcinol.

6. A process according to claim 4 wherein the precondensation productsare of formaldehyde and 1.3 dihydroxy 6. chloro-henzene.

7. In a process of improving the physical and chemical properties ofwool, the steps which comprise dissolving (b) a compound of the classconsisting of resorcinol and chloro-substituted resorcinols in anaqueous acid solution of (a) formaldehyde having a pH value between 5and 2.8, the molecular ratio of (a) to (b) being at least 6:1, heatingthe solution to a temperature of the order of 60 C. for a period ofabout one-half hour whereby there are formed precondensation products,adding wool to the solution and subjecting the same to treatmenttherewith for about onehalf hour while maintaining the temperature ofthe solution at 40-45 C., removing, hydroextracting, and drying the wooland hardening at a temperature above 100 C.

8. In a. process of improving the physical and chemical properties offelt, the steps which comprise dissolving (b) a compound of the classconi sisting of resorcinol and chloro-substituted resorcinois in anaqueous acid solution of (a) formaldehyde having a pH value between 5and 2.8, the molecular ratio of (a) to (b) being at least 6:1, heatingthe solution to a temperature of the order of 60 C. for a period ofabout one-half hour whereby there areformed precondensation products,adding felt to the solution and subjecting the same to treatmenttherewith for about 6 hours while maintaining the temperature of thesolution at about 35 C., removing, hydroextracting, and drying the feltand hardening at about 105 C.

9. In a process of improving the physical and chemical properties ofwool, the steps which comprise dissolving (b) a compound of the classconsisting of resorcinol and chloro-substituted resorcinols in anaqueous acid solution of (a) formaldehyde having a pH value between 5and 2.8 and in which at least 6 mols of (a) per mol of (b) are used,heating the solution at about 60 C. for approximately one-half hourwhereby there are formed precondensation products, diluting the solutionwith water and adjusting the temperature to 40-45 0., adding woolthereto and treating the same about one-half hour, removing,hydroextracting, and drying the wool and hardening the REFERENCES CITEDThe following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,395,733 Romer Nov. 1, 19212,234,138 Kritchevsky Mar. 4, 1941 2,240,388 Calva Apr. 29, 19412,348,602 Calva May 9, 1944 2,390,073 Calva Dec. 4, 1945

1. A PROCESS OF IMPROVING THE PHYSICAL AND CHEMICAL PROPERTIES OFKERATINACEOUS ANIMAL FIBERS, WHICH COMPRISES THE STEPS OF TREATING THEFIBERS WITH A WEAKLY ACIDIC SOLUTION CONTAINING PRECONDENSATION PRODUCTSOF (A) FORMALDEHYDE AND (B) A COMPOUND OF THE CLASS CONSISTING OFRESORCINOL AND CHLORO-SUBSTITUTED RESORCINOLS IN THE PREPARATION OFWHICH AT LEAST SIX MOLS OF (A) PER MOL OF (B) ARE EMPLOYED, CENTRIFUGINGTHE THUS TREATED FIBERS AND DRYING THE SAME BY HEATING.